In recent years, interface devices in which an image recognition device, such as a camera, and a projector are combined have been developed. These interface devices read an object, and a gesture by a hand or a finger with the camera. Then, these interface devices perform identification and recognition of the object and recognition of the gesture by image processing, and provide information in accordance with the result by a picture image irradiated from the projector. In addition, these interface devices read and use, as input, the gesture by a hand or a finger with respect to the picture image irradiated from the projector. Examples of these interface devices include those described in Non Patent Literatures 1 to 3 (NPLs 1 to 3).
In an interface device as described above, a projector is an important component. In order to reduce the interface device in size and weight, the projector needs to be reduced in size and weight. At the present day, a compact and lightweight projector like this is called a picoprojector. Picoprojectors like this are disclosed in Non Patent Literatures 4 to 6 (NPLs 4 to 6).
Here, reducing the projector in size and weight and brightening output of the projector is a trade-off relationship. For example, in NPL 4, the brightness of output is in the highest category among picoprojectors, and the size is also in the biggest category among picoprojectors. Specifically, the projector has a volume of 160 cc and a weight of 200 g. The projector outputs a light flux of 33 lm by a 12 W LED light source. In contrast, a picoprojector described in NPL 5 is more reduced in size and weight compared to the projector described in NPL 4, but the brightness of output is about half of that of the projector described in NPL 4. Specifically, the projector described in NPL 5 has a volume of 100 cc, a weight of 112 g, a power consumption of 4.5 W, and a brightness of 15 lm.